Ga / Sm doped SiO2 / LATP co-coated high-nickel positive electrode material and preparation method

Abstract

The application discloses a preparation method of Ga / Sm doped SiO2 / LATP co-coated high-nickel positive electrode material, and the method comprises the following steps: S1, obtaining a doped base material; S2, adding tetraethyl orthosilicate and LATP into a solvent, uniformly mixing, adding an acidic adjusting agent into the solvent, adjusting pH, and preparing an acidic spray coating liquid; S3, performing acidic spray coating on the doped base material and performing drying treatment; and S4, obtaining the Ga / Sm doped SiO2 / LATP co-coated high-nickel ternary positive electrode material. The coating is dissolved in an organic acid solvent, and then the high-nickel positive electrode material is subjected to spray coating, so that the residual alkali content on the surface of the material is effectively reduced, the water washing process is avoided, the SiO2 / LATP coating layer slows down the phase transition speed of the positive electrode material in the cycle process, the interface stability is improved, and the structural stability of the electrode surface is maintained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion battery materials, and particularly relates to a Ga / Sm doped SiO2 / LATP co-coated high-nickel positive electrode material and a preparation method thereof. BACKGROUND

[0002] Lithium battery high-nickel ternary lithium nickel cobalt manganese oxide (NCM) or lithium nickel cobalt aluminum oxide (NCA) positive electrode material is widely used in portable devices, electric vehicles and energy storage fields due to its high specific capacity, low cost and environmental friendliness. However, due to its poor thermal stability and cycle stability, there is a certain safety hazard in actual application, which greatly limits its large-scale application. The reason is that a large amount of free lithium exists on the surface of the ternary material during production, which has a great influence on the material post-processing, storage and charge-discharge. The product after high-temperature calcination during the production and synthesis of the ternary positive electrode material is mainly the oxide of Li, which is easy to react with H2O and CO2 in the air to generate LiOH and Li2CO3 again, and is left on the surface of the material, making the pH value of the material higher. Especially in high-nickel ternary materials, as the nickel content increases, the sintering temperature becomes lower, resulting in a decrease in the volatilization amount of lithium salt, and then an increase in the content of lithium salt left on the surface of the material, and a greater alkalinity of the material. The surface Li2CO3 decomposes at high voltage, which is one of the main reasons for the battery swelling, thereby bringing about safety hazards. In addition, the cationic disordering of Li + / Ni 2+ , the corrosion of HF generated by the side reaction of the electrolyte and the irreversible capacity loss caused by the dissolution of the surface transition metal also deteriorate the cycle performance.

[0003] For the above problems, the most common solution at present is to dope, wash and coat the ternary material.

[0004] Commonly used bulk phase doping cations have an ionic radius smaller than or close to that of Ni 2+ (0.069nm) and occupy transition metal sites, such as Al 3+ / Si 4+ / V 5+ / Nb 5+ , which form strong M-O bonds in the transition metal layer during the charge-discharge process of the electrode, preventing the migration of Ni 2+ to the lithium layer, and effectively alleviating the degradation of the material lattice structure and improving the cycle stability of the material. When the ionic radius of the doping cation is close to or slightly larger than that of Li + (0.076nm), such as Mg 2 + 、 Zr 4+ 、Zn 2+, then enters the lithium ion layer and is bonded to the adjacent transition metal layer through O-M-O, and when the amount of lithium is large in the deep charge of the electrode, the layered structure can be supported from collapsing, and the structural stability of the material at high pressure is improved; at the same time, the reduction of the repulsive force between the oxygen layers also inhibits the Ni 2+ Migration to the lithium layer.

[0005] There are two common water washing methods: one is to first wash with pure water and then dry coating, that is, the material is washed with water under the action of appropriate material liquid ratio, temperature, rotation speed and time, and then dehydrated and dried, and the dried powder is then dry mixed and coated, and the coated material is sintered to obtain the finished product. Since high-nickel ternary materials are sensitive to water, long-time direct water washing will cause Li + dissolution, generate NiO without electrochemical activity, destroy the surface phase structure of the material, and thus affect the electrochemical performance of the material. In addition, after water washing, the material needs to be dehydrated and then dried, and dehydration will cause loss of raw materials, and the drying process will cause Li + extraction, affecting the water washing effect. After drying, dry coating is performed, which will affect the uniformity of the coated material mixture, further affecting the electrochemical performance of the high-nickel material. The second is solution water washing and coating, that is, using water, inorganic or organic substances as solvents to prepare oxide or salt solutions, mixing high-nickel ternary materials with the prepared solutions, stirring under certain conditions, and then directly drying and sintering to obtain the finished product. However, the preparation of oxide or salt solution in this scheme is complex, and the oxide or salt is not soluble in the solvent, which will cause the agglomeration of the solute during the subsequent drying process, thereby affecting the uniformity of the coating and the electrochemical performance of the material.

[0006] The common coating method for positive electrode materials is generally sol-gel or high-temperature solid phase method. Sol-gel method generally requires freeze-drying, which is not suitable for large-scale industrialization; and the coating layer of high-temperature solid phase method is not uniform, which has a certain influence on the performance of high-nickel ternary materials.

[0007] In summary, single bulk doping and coating cannot solve the problem of unstable material surface interface, and the water washing and coating process is not easy to control, which easily causes lattice defects and uneven coating, reduces the discharge capacity of the ternary positive electrode material, and is more prone to micro-cracks during storage and discharge, and the stability and storage performance of the material have not been effectively improved. Therefore, it is necessary to combine doping and coating through a simple and fast process method to comprehensively and significantly improve the comprehensive performance of high-nickel positive electrode materials. SUMMARY

[0008] In view of the problems existing in the doping, water washing and coating process of high nickel ternary material, the application provides a Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material and a preparation method, so as to solve the problems of unstable and uneven material surface interface, poor conductivity, Li + leaching in the surface lattice, raw material loss and reduced discharge capacity of the ternary positive electrode material in the prior art.

[0009] The application provides a preparation method of a Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material, which comprises the following steps:

[0010] S1, a nickel-cobalt-manganese ternary composite precursor is weighed, a certain amount of Ga and Sm containing compound and a certain amount of lithium source compound are weighed according to the metal content of nickel, cobalt and manganese in the nickel-cobalt-manganese ternary composite precursor, and the mixture is uniformly mixed and calcined to obtain a doped base material;

[0011] S2, tetraethyl orthosilicate and LATP are added to a solvent, uniformly mixed, and an acid regulator is added thereto to adjust the pH to prepare an acid spray coating liquid;

[0012] S3, the doped base material is subjected to acid spray coating and drying treatment;

[0013] S4, the dried product in S3 is calcined again to obtain a Ga / Sm doped SiO2 / LATP co-coated high nickel ternary positive electrode material.

[0014] Preferably, the metal molar ratio of nickel in the nickel-cobalt-manganese ternary composite precursor material in S1 is 0.75-0.95, the metal molar ratio of cobalt is 0.025-0.15, and the metal molar ratio of manganese is 0.005-0.2, and the nickel-cobalt-manganese ternary precursor is one or more of nickel-cobalt-manganese hydroxide and / or nickel-cobalt-manganese oxide and / or nickel-cobalt-manganese carbonate.

[0015] Preferably, the doping molar amount of Ga and Sm in S1 is 0.01-1% of the total metal molar amount of nickel, cobalt and manganese in the nickel-cobalt-manganese precursor, and the Ga and Sm containing compound is one or more of Ga and Sm oxides, carbonates, nitrates and organic salts.

[0016] Preferably, the ratio of lithium to the total metal molar amount of nickel, cobalt, manganese, gallium and samarium in the lithium source is (1.2-0.9):1, and the lithium source is one or more of lithium containing carbonates, hydroxides, oxides, sulfates and nitrates.

[0017] Preferably, the mixing method in S1 is one or a combination of ball milling, mechanical stirring, magnetic stirring or mortar grinding.

[0018] Preferably, the calcination temperature in S1 is 700-850 DEG C, the time is 4-20h, and the temperature rising rate is 2-5 DEG C / min, which avoids slow temperature rising, resulting in that the primary particles formed after calcination of the positive electrode material are not long; and the primary particles are too large when the temperature rising rate is too fast, although the cycle stability of the positive electrode material is improved, but the capacity of the finally formed material is affected.

[0019] Preferably, the solvent in S2 is one or more of water, ethanol, ethylene glycol and n-butanol.

[0020] Preferably, the acid regulator in S2 is one or more of citric acid, salicylic acid, acetic acid and oxalic acid.

[0021] Preferably, the mass ratio of the tetraethyl orthosilicate to the solvent in S2 is (0.1-0.5):10; the mass ratio of the LATP to the solvent is (0.1-0.5):10; and then the acid regulator is gradually added into the coating liquid until the pH value of the coating liquid is 2-5.5.

[0022] Preferably, the mass ratio of the acid coating liquid to the doping matrix material in S3 is 5-25%, and the mixture after the spray coating is dried at 80-120 DEG C for 2-8h.

[0023] If the mass ratio of the coating liquid to the ternary material exceeds 25%, the liquid amount of the coating solution is excessive during the spray coating, which greatly increases the thickness of the coating layer, resulting in poor conductivity of the material and decreased electrochemical capacity. If the mass ratio of the coating solution to the lithium nickel-manganese oxide primary product is less than 5%, the amount of the coating solution is insufficient, which is not enough to cover and contact the ternary material with the coating solution, and is also not conducive to the improvement of the electrochemical stability of the finally prepared material.

[0024] Preferably, the calcination temperature in S4 is 300-700 DEG C, the temperature rising rate is 3-8 DEG C / min, and the calcination time is 3-10h, and the calcination atmosphere is oxygen.

[0025] The application also provides a Ga / Sm doped SiO2 / LATP co-coated high-nickel positive electrode material prepared by the above preparation method.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] 1. The Ga / Sm is doped into the Ni 3+ metal layer and the Li + layer respectively, the lithium and nickel mixing is inhibited, the valence state does not change during charging and discharging, the volume does not change, the Ga / Sm can play a role of framework, stabilize the crystal structure, and improve the cycle life and safety performance of the material;

[0028] 2. The acid spray of this invention can neutralize the alkali on the surface of the material, easily remove alkaline substances from the surface of high-nickel materials, and eliminate the need for water washing of high-nickel materials. At the same time, the spray coating protects the substrate surface, atomizes the coating elements into extremely fine liquid droplets, and then coats them onto the surface of the positive electrode material, achieving a coating effect of small amount and uniform distribution. This process integrates acid washing and coating.

[0029] 3. Compared with the commonly used sol-gel method or high-temperature solid phase method, spray coating produces a more uniform coating layer. At the same time, the coating amount can be adjusted to more effectively meet the requirements of material rate performance and cycle stability.

[0030] 4. The SiO2 in the SiO2 / LATP coating layer of this invention can preferentially react with the byproduct HF in the electrolyte, preventing HF from reacting with the surface of the electrode material, thereby significantly improving the problem of battery capacity decay.

[0031] 5. The LATP in the SiO2 / LATP coating layer of this invention possesses a stable and rapid lithium-ion transport channel, which can improve the poor conductivity of the SiO2 coating layer, which is unfavorable for Li-ion transport. + Regarding the issue of ion transport, the SiO2 / LATP coating ultimately isolates the positive electrode material from direct erosion by air and electrolyte, slows down the phase transition rate of the positive electrode material during cycling, improves interfacial stability, and maintains the structural stability of the electrode surface. Attached Figure Description

[0032] Figure 1 This is a scanning SEM image of the high-nickel material co-coated with SiO2 / LATP by acid spraying in Example 1.

[0033] Figure 2 The image shows a scanning SEM image of the high-nickel material co-coated with a dry-mixed SiO2 / LATP mixture, as shown in Comparative Example 5. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] S1. Weigh a certain mass of Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor, then press M Ga :M (Ni+Co+Mn） =0.5%, M Sm :M(Ni+Co+Mn） Ga2O3 and Sm2O3 were weighed at a ratio of 0.5%. Then lithium hydroxide was weighed at a ratio of M Li :M (Ni+Co+Mn+Ga+Sm) =1.05:1 and added to a high-speed mixer for mixing. Then the mixture was placed in a sintering furnace and sintered at 800°C for 10h at a temperature rising rate of 3°C / min under an oxygen atmosphere to obtain Ga / Sm-doped ternary matrix material.

[0037] S2, 0.2g of tetraethyl orthosilicate and 0.2g of LATP were weighed into 10g of ethanol and stirred until uniform. Then citric acid was added to the mixture until the solution had a pH of 5.0 to obtain an acidic coating solution.

[0038] S3, 100g of the doped ternary matrix material in S1 was placed in a spray coating device. The acidic coating solution in S2 was sprayed onto the matrix material through the nozzle of the spray coating device. Finally, the coated mixture was vacuum dried at 100°C for 6h.

[0039] S4, the dried coated product was placed in a sintering furnace and sintered at 500°C for 6h at a temperature rising rate of 5°C / min under an oxygen atmosphere to obtain Ga / Sm-doped SiO2 / LATP co-coated high-nickel positive electrode material.

[0040] Example 2

[0041] A certain amount of Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor in S1 of Example 1 was weighed, then Ga2O3 and Sm2O3 were weighed at a ratio of M Ga :M (Ni+Co+Mn） =0.5%, and the remaining synthesis steps were the same as in Example 1 to obtain Ga-doped SiO2 / LATP co-coated high-nickel positive electrode material. Sm :M (Ni+Co+Mn） =0.5% was changed to weighing a certain amount of Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor, then Ga2O3 was weighed at a ratio of M Ga :M (Ni+Co+Mn） =0.5%, and the remaining synthesis steps were the same as in Example 1 to obtain Ga-doped SiO2 / LATP co-coated high-nickel positive electrode material.

[0042] Example 3

[0043] A certain amount of Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor in S1 of Example 1 was weighed, then Ga2O3 and Sm2O3 were weighed at a ratio of M Ga :M (Ni+Co+Mn） =0.5%, and the remaining synthesis steps were the same as in Example 1 to obtain Ga-doped SiO2 / LATP co-coated high-nickel positive electrode material.Sm :M (Ni+Co+Mn） =0.5% of the proportion of Ga2O3 and Sm2O3 is changed to weigh a certain mass of Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor, then according to M Sm :M (Ni+Co+Mn） =0.5% of the proportion of Sm2O3, and the remaining synthesis steps are the same as in Example 1, to obtain Sm-doped SiO2 / LATP co-coated high-nickel positive electrode material.

[0044] Example 4

[0045] In S2 of Example 1, 0.2g of tetraethyl orthosilicate and 0.2g of LATP are added to 10g of ethanol and stirred uniformly, which is changed to weighing 0.2g of tetraethyl orthosilicate and adding it to 10g of ethanol and stirring uniformly, and the remaining synthesis steps are the same as in Example 1, to obtain Ga / Sm-doped SiO2-coated high-nickel positive electrode material.

[0046] Example 5

[0047] In S2 of Example 1, 0.2g of tetraethyl orthosilicate and 0.2g of LATP are added to 10g of ethanol and stirred uniformly, which is changed to weighing 0.2g of LATP and adding it to 10g of ethanol and stirring uniformly, and the remaining synthesis steps are the same as in Example 1, to obtain Ga / Sm-doped SiO2-coated high-nickel positive electrode material.

[0048] Example 6

[0049] In S1 of Example 1, 0.2g of tetraethyl orthosilicate and 0.2g of LATP are added to 10g of ethanol and stirred uniformly, which is changed to weighing 0.2g of tetraethyl orthosilicate and 0.1g of LATP and adding them to 10g of ethanol and stirring uniformly, and the remaining synthesis steps are the same as in Example 1, to obtain SiO2 / LATP co-coated high-nickel positive electrode material.

[0050] Comparative Example 1

[0051] This comparative example does not contain the doping and coating process. According to the total amount of nickel, cobalt and manganese metals in the Ni 0.83 Co 0.11 Mn 0.06 (OH)2 precursor, lithium hydroxide is weighed according to the lithium source to precursor molar ratio Li / (Ni+Co+Mn)=1.05:1 and added to a high-speed mixer and mixed uniformly. Then the mixture is placed in a sintering furnace and sintered at 800℃ with a heating rate of 3℃ / min for 10h in an oxygen atmosphere to obtain a high-nickel positive electrode material.

[0052] Comparative Example 2

[0053] The Ga2O3 and Sm2O3 were not added to the precursor in S1 of Example 1, and the remaining synthesis steps were the same as those of Example 1 to obtain the SiO2 / LATP co-coated high-nickel positive electrode material.

[0054] Comparative Example 3

[0055] The present comparative example only contains S1 in Example 1 and does not contain the coating process to obtain the Ga / Sm doped high-nickel positive electrode material.

[0056] Comparative Example 4

[0057] Comparative Example 4 is a common spray coating, which is not an acidic spray coating. In S2 of Example 1, 0.2 g of tetraethyl orthosilicate and 0.2 g of LATP are added to 10 g of ethanol, stirred uniformly, and configured into a coating liquid without adding citric acid. The remaining synthesis steps are the same as those of Example 1.

[0058] Comparative Example 5

[0059] Comparative Example 5 is a common dry mixing coating, which is not an acidic spray coating.

[0060] S1, consistent with S1 in Example 1;

[0061] S2, 0.2 g of SiO2 and 0.2 g of LATP and 100 g of doped ternary matrix material are weighed and added to a high-speed mixer for uniform mixing;

[0062] S3, the S2 mixture is placed in a sintering furnace, sintered at 500°C for 6 h under an oxygen atmosphere at a temperature rising rate of 5°C / min to obtain the Ga / Sm doped SiO2 / LATP double-coated high-nickel positive electrode material.

[0063] Electrochemical performance test:

[0064] The Ga / Sm doped SiO2 / LATP co-coated high-nickel positive electrode material prepared by the present patent technology is a positive electrode, and a coin cell is assembled for electrochemical performance test. The specific steps are as follows:

[0065] The positive active material, carbon black SuperP, and polyvinylidene fluoride (Solvey5130) (mass fraction 5 %, solvent N-methyl pyrrolidone) are mixed in a mass ratio of 90:5:5 to form a slurry, which is uniformly coated on the surface of an aluminum foil to obtain a positive electrode sheet. Then, a lithium sheet is used as a negative electrode sheet, and a 1 mol / L lithium hexafluorophosphate solution in ethylene carbonate (EC) and dimethyl carbonate (DMC) (mass ratio of EC to DMC is 1:1) is used as an electrolyte. A lithium ion battery is assembled in a glove box.

[0066] The lithium ion battery is tested for cycle performance by using an electrochemical tester, the test temperature is 25°C, the rate performance of the battery is tested at 3.0-4.3 V, 0.1C, 0.5C, 1C, 2C, 0.1C rate under the condition of 25°C, and the cycle performance is tested at 3.0-4.3 V, 1 C current density under the condition of 25°C.

[0067] Table 1: 25°C, 3-4.3V, 0.1C electrochemical cycle performance of examples and comparative examples

[0068] Sample Doping element Coating liquid Coating layer Coating method 25°C 4.3V (Vs. Li) discharge test 100 cycles capacity retention rate (%) Example 1 Ga / Sm Acidic coating liquid SiO2 / LATP Spray coating 95.7 Example 2 Ga Acidic coating liquid SiO2 / LATP Spray coating 91.7 Example 3 Sm Acidic coating liquid SiO2 / LATP Spray coating 91.4 Example 4 Ga / Sm Acidic coating liquid SiO2 Spray coating 87.9 Example 5 Ga / Sm Acidic coating liquid LATP Spray coating 87.3 Example 6 Ga / Sm Acidic coating liquid SiO2 / LATP Spray coating 93.7 Comparative Example 1 - - - - 65.2 Comparative Example 2 - Acidic coating liquid SiO2 / LATP Spray coating 85.6 Comparative Example 3 Ga / Sm - - - 70.8 Comparative Example 4 Ga / Sm - SiO2 / LATP Spray coating 84.4 Comparative Example 5 Ga / Sm - SiO2 / LATP Dry mixing coating 82.2

[0069] As can be seen from Table 1, the cycle stability (all greater than 87%) of the high-nickel materials coated with acidic spray in Examples 1-6 is higher than that of Comparative Example 5 (82.2%) coated with dry mixing;

[0070] As can be seen from Example 1 and Comparative Example 4, under the premise of both being high-nickel materials coated by spraying, the stability (95.7) of Example 1 using an acidic coating solution is much higher than that (84.4%) of Comparative Example 4 without using an acidic coating solution, confirming that acidic spray coating is beneficial to improving the electrochemical cycle stability of high-nickel materials.

[0071] Examples 1-3 are all high-nickel materials containing doping elements, and the cycle stability of Examples 1-3 is higher than that of Comparative Example 2 which does not contain doping elements, confirming that the presence of doping elements has the function of stabilizing the crystal structure and improving the cycle life of the material. At the same time, the stability of the double-metal-doped Example 1 is higher than that of the single-metal-doped Examples 2-3, confirming that double doping of the metal layer and Li 3+ layer can jointly stabilize the structure of the metal layer and lithium layer of the material, and further improve the cycle stability of the material. +

[0072] At the same time, the material stability of Examples 1-3 (all higher than 91%) and Example 6 (93.7%) coated with SiO2 / LATP is higher than that of Example 4 (87.9%) coated with only SiO2 and Example 5 (87.3%) coated with only LATP, confirming that SiO2 / LATP co-coating, compared with single material coating, further isolates the direct corrosion of air and electrolyte on the positive electrode material, slows down the phase transition speed of the positive electrode material during the cycle process, improves the interface stability, and increases the electrochemical cycle stability.

[0073] The stability of Example 1 (95.7%) coated with SiO2 / LATP is higher than that of Example 6 (93.7%) coated with SiO2 / LATP with a decrease in the content of LATP.

[0074] Table 2: Rate performance of Example 1, Example 6 and Comparative Example 1

[0075] ​ Sample 0.1C discharge capacity mAh / g 0.5C discharge capacity mAh / g 1C discharge capacity mAh / g 2C discharge capacity mAh / g Example 1 212.2 207.1 196.1 189.2 Example 4 209.2 195.3 170.4 150.5 Example 6 211.0 205.6 192.7 180.4

[0076] Meanwhile, from Table 2, the 0.5C, 1C and 2C capacity of Example 6 are all lower than Example 1, but meanwhile higher than Example 4 without LATP, which confirms that with the increase of LATP content, it is easier to relieve the SiO2 inertness, form a fast lithium ion transmission channel, and more effectively improve the rate performance of high-nickel ternary.

[0077] Table 3: Surface residual alkali content test results of Example 1, Comparative Example 1 and Comparative Examples 3-5

[0078] Sample Surface residual alkali content (wt%) Example 1 0.334 Comparative Example 1 2.228 Comparative Example 3 2.028 Comparative Example 4 1.227 Comparative Example 5 1.436

[0079] By acid-base potentiometric titration (Switzerland Wanthong 905 type potentiometric titrator), the free surface residual alkali content is measured. From Table 3, the surface alkali content of Example 1 using acid spray (0.334) is much lower than Comparative Example 1 and Comparative Examples 3-5 without using acid spray. These two results together confirm that the use of acid spray can reduce the surface alkali content of the material, and thus improve the stability of the material.

[0080] From Table 2, the 0.5C, 1C and 2C capacity of Example 6 are all lower than Example 1, but meanwhile higher than Example 4 without LATP, which confirms that with the increase of LATP content, it is easier to relieve the SiO2 inertness, form a fast lithium ion transmission channel, and more effectively improve the rate performance of high-nickel ternary. Figure 1 - Figure 2 From Table 2, the 0.5C, 1C and 2C capacity of Example 6 are all lower than Example 1, but meanwhile higher than Example 4 without LATP, which confirms that with the increase of LATP content, it is easier to relieve the SiO2 inertness, form a fast lithium ion transmission channel, and more effectively improve the rate performance of high-nickel ternary. Figure 1 From Table 2, the 0.5C, 1C and 2C capacity of Example 6 are all lower than Example 1, but meanwhile higher than Example 4 without LATP, which confirms that with the increase of LATP content, it is easier to relieve the SiO2 inertness, form a fast lithium ion transmission channel, and more effectively improve the rate performance of high-nickel ternary. Figure 2 From Table 2, the 0.5C, 1C and 2C capacity of Example 6 are all lower than Example 1, but meanwhile higher than Example 4 without LATP, which confirms that with the increase of LATP content, it is easier to relieve the SiO2 inertness, form a fast lithium ion transmission channel, and more effectively improve the rate performance of high-nickel ternary.

[0081] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the scope of the present application shall be included in the protection scope of the present application.

Claims

1. A preparation method of Ga / Sm-doped SiO2 / LATP co-coated high-nickel positive electrode material, characterized in that, The method comprises the following steps: S1, weigh the nickel-cobalt-manganese ternary composite precursor, weigh a certain amount of Ga and Sm containing compounds and a certain amount of lithium source compounds according to the metal content of nickel, cobalt and manganese in the nickel-cobalt-manganese ternary composite precursor, mix uniformly and then calcine to obtain a doped base material; the molar ratio of nickel, cobalt and manganese in the nickel-cobalt-manganese ternary composite precursor is (0.75-0.95):(0.025-0.15):(0.005-0.2); the doping molar amount of Ga and Sm is 0.01-1% of the total molar amount of nickel, cobalt and manganese in the nickel-cobalt-manganese precursor; the molar ratio of lithium in the lithium source to the total metal molar amount of nickel, cobalt, manganese, gallium and samarium is (1.2-0.9):1; S2, add tetraethyl orthosilicate and LATP into a solvent, mix uniformly, and then add an acidic adjusting agent to adjust the pH to prepare an acidic spray coating liquid; the mass ratio of tetraethyl orthosilicate to the solvent is (0.1-0.5):10; the mass ratio of LATP to the solvent is (0.1-0.5):10; then gradually add the acidic adjusting agent to the coating liquid until the pH value of the coating liquid is 2-5.5; S3, spray coat the doped base material with the acidic spray coating liquid and dry the mixture; the mass ratio of the acidic spray coating liquid to the doped base material is 5-25%; S4, calcine the dried product in S3 again to obtain a Ga / Sm doped SiO2 / LATP co-coated high-nickel ternary positive electrode material.

2. The preparation method of the Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 1, characterized in that, The nickel-cobalt-manganese ternary precursor in S1 is one or more of nickel-cobalt-manganese hydroxide, nickel-cobalt-manganese oxide and nickel-cobalt-manganese carbonate.

3. The preparation method of the Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 2, characterized in that, The Ga and Sm containing compounds in S1 are one or more of Ga and Sm oxides, carbonates, nitrates and organic salts.

4. The preparation method of the Ga / Sm-doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 3, characterized in that, The lithium source is one or more of lithium containing carbonates, hydroxides, oxides, sulfates and nitrates.

5. The preparation method of the Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 4, characterized in that, The mixing method in S1 is one or a combination of ball milling, mechanical stirring, magnetic stirring and mortar grinding.

6. The preparation method of the Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 5, characterized in that, The calcination temperature in S1 is 700-850°C, the calcination time is 4-20h, and the heating rate is 2-5°C / min.

7. The preparation method of a Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 1, characterized in that, The solvent in S2 is one or more of water, ethanol, ethylene glycol and n-butanol.

8. The preparation method of a Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 7, characterized in that, The acidic adjusting agent in S2 is one or more of citric acid, salicylic acid, acetic acid and oxalic acid.

9. The preparation method of a Ga / Sm doped SiO2 / LATP co-coated high nickel positive electrode material according to claim 1, characterized in that, The drying treatment in S3 dries the spray coated mixture at 80-120°C for 2-8h.

10. The preparation method of a Ga / Sm doped SiO2 / LATP co-coated high nickel cathode material according to claim 1, characterized in that, The calcination temperature in S4 is 300-700°C, the heating rate is 3-8°C / min, the calcination time is 3-10h, and the calcination atmosphere is oxygen. 11.A Ga / Sm doped SiO 2 / LATP co-coated high nickel cathode material, characterized in that, The co-coated high-nickel positive electrode material is prepared by the preparation method in any one of claims 1-10.

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